Dreadlocks, cornrows, twisted braids and other hairstyles popular among African American women will be more accepted across the military after a forcewide review of hairstyle policies prompted several changes, Defense Secretary Chuck Hagel said.

The three-month review came after a spate of complaints that service-level grooming policies were racially biased against black women who choose to wear their hair naturally curly rather than use heat or chemicals to straighten it.

“Each service reviewed its hairstyle policies to ensure standards are fair and respectful while also meeting military requirements,” Hagel wrote in a letter to lawmakers on Capitol Hill notifying them of the changes Monday. “These reviews were informed by a panel of military personnel of mixed demographics reflective of our diverse force.”

The Marine Corps agreed to hold a special meeting of its uniform board later this year and is conducting a forcewide survey about whether the “twist” or “dreadlocks” styles should be permitted while in uniform.

The review concluded that the terms “matted and unkempt,” which the Army and Air Force used to describe some dreadlocks and braids, are “offensive” and were removed from service grooming policies, Hagel said.

For some women, the hair regulations were derailing otherwise promising careers. For example, Navy Hospital Corpsman 2nd Class Jessica Sims, a 12-year sailor, wears her hair in long, tightly twisted locks pulled into a bun when she’s in uniform.

No commanders ever complained about her hair, Sims said, until she was assigned as a teacher at the Navy’s boot camp, Recruit Training Command Great Lakes in Illinois. There, the 32-year-old sailor with an unblemished record was told to cut her hair or wear a wig, and when she refused, her commanders processed her for separation for “serious misconduct.”